How to create moving, dynamic/animated fog/clouds?
As Yohello says you could use the Principled Volume and plug it into the Volume socket of the Material Output. Here is a basic way to do it (perhaps not the most realistic solution though, but you'll find other ones on youtube or maybe someone will propose here?):

Create a basic elongated shape, subdivide it a bit, give it a Subdivision Surface modifier.

Create this node chain: Texture Coordinate &gt; Mapping &gt; Noise Texture &gt; ColorRamp.

Plug the Noise Texture into a Vector &gt; Displacement node to give it a bit of 3D relief (don't forget to enable the Displacement &gt; Displacement Only option in the Properties panel &gt; Material &gt; Settings &gt; Surface).

Plug the Noise into the Density socket of the Principled Volume.

Now play with the Location values of the Mapping node in order to make the cloud shape evolve through time.